A scan type distance measuring apparatus has been proposed to measure a distance to a measurement target using a laser beam. This distance measuring apparatus has a launch unit that launches a laser beam (or laser pulses) emitted from a laser light source at a constant timing, for example, by using a MSMS (Micro Electro Mechanical System) mirror, for example, to scan the laser beam two-dimensionally. In addition, this distance measuring apparatus has a light receiving unit. With respect to the scan of the laser beam by the launch unit, a photodetector of the light receiving unit detects reflected light from the measurement object, and computes the distance to the measurement target for every scan position.
The distance measuring apparatus may be applied to detect various measurement targets including biometrics such as humans or the like, and objects such as vehicle or the like. The distance measuring apparatus may output a range image (or depth map) in which distance values at each of range (or distance) measurement points are arranged in an order of the raster scanned samples, for example. In this case, the distance measuring apparatus can detect an athlete, such as a gymnast, a basketball player, or the like, using the range image, and measure a form of the athlete, such as a form of a performance of the gymnast, a shooting form of the basketball player, or the like. The form or movement of the athlete can be analyzed based on the form of the athlete measured by the distance measuring apparatus. For example, in a case in which the form or movement of the gymnast is measured by the distance measuring apparatus, scoring or the like of the performance of the gymnast can be made based on the analyzed form or movement.
However, one distance measuring apparatus makes the measurement to the measurement target in one direction. It is not possible to measure the distance to a part of the measurement target not hit by the laser beam, such as a rear of the measurement target. Accordingly, a system has been proposed to make the measurement to the measurement target in a plurality of different directions, using a plurality of distance measuring apparatuses. However, in a case in which first and second distance measuring apparatuses are arranged at mutually opposing positions, for example, the first distance measuring apparatus may detect the laser beam launched from the second distance measuring apparatus. In this case, the first distance measuring apparatus erroneously detects the laser beam launched from the second distance measuring apparatus, as if the laser beam were the reflected light of the laser beam launched from the first distance measuring apparatus. Consequently, even if measured results of the first and second distance measuring apparatuses are integrated into a single measured result, it is difficult to accurately measure the movement or the like of the measurement target based on the single measured result.
The distance measuring apparatus may have a synchronization mechanism that scans the laser beam one-dimensionally using a rotation mechanism including a rotation mirror. This distance measuring apparatus receives the reflected light from the same direction in which the laser beam is launched. For this reason, Japanese Laid-Open Patent Publication No. 2011-112503 proposes adjusting a rotational speed of the rotation mirror of the first distance measuring apparatus when the rotation angle of the rotation mirror falls within an angular range in which the erroneous detection of the laser beam launched from the second distance measuring apparatus occurs. By adjusting the rotational speed of the rotation mirror of the first distance measuring apparatus in this manner, it is possible to prevent the first distance measuring apparatus from erroneously detecting the laser beam launched from the second distance measuring apparatus, as if the laser beam were the reflected light of the laser beam launched from the first distance measuring apparatus.
On the other hand, the distance measuring apparatus may have a separation structure to separate the launching light and the received light, that scans the laser beam two-dimensionally without using the rotation mechanism. In this case, a reception unit detects the scan range of the laser beam launched from the launch unit. For this reason, in a case in which the measurement target is measured from a plurality of different directions, the scan ranges of the laser beams launched from the plurality of distance measuring apparatuses interfere with each other. For example, there exists a timing at which the scan direction of the first distance measuring apparatus matches the scan direction of the second distance measuring apparatus that is arranged at a position opposing the first distance measuring apparatus. At this timing at which the scan direction of the first distance measuring apparatus matches the scan direction of the second distance measuring apparatus, the second distance measuring apparatus, for example, erroneously detects the laser beam launched from the first distance measuring apparatus, as if the laser beam were the reflected light of the laser beam launched from the second distance measuring apparatus. Accordingly, when using the plurality of distance measuring apparatus respectively having the separation structure to detect the scan range of the launched laser beam, it is difficult to prevent the distance measuring apparatus from erroneously detecting the laser beam launched from the opposing distance measuring apparatus, as if the laser beam were the reflected light of the laser beam launched therefrom.
Therefore, when conventionally using the plurality of distance measuring apparatus respectively having the structure to detect the scan range of the launched laser beam, and measuring the measurement target from the plurality of different directions, the scan ranges of the laser beams launched from the plurality of distance measuring apparatuses interfere with each other. For this reason, the distance measuring apparatus erroneously detects the laser beam launched from the opposing distance measuring apparatus, as if the laser beam were the reflected light of the laser beam launched therefrom.
Related art includes Japanese Laid-Open Patent Publications No. 2011-112503, No. 2014-052274, No. 2005-221333, and No. 2006-308482.